The present invention relates to an image forming method for forming a transferred image on the surface of an image receiving member.
As a method for forming an image on a transfer member such as paper and a film, a thermal transfer method can be presented.
The thermal transfer method comprises the steps of superimposing a transfer member (toner sheet) with a transfer layer of a pigment-based toner formed on the surface of a supporting member as a transfer material, on an image receiving member (image receiving sheet) such as paper and a film, and applying heat on the image from the back side of the supporting member of the toner sheet by a thermal head, a laser head, or the like for transferring the toner onto the image receiving sheet so as to form the image on the image receiving sheet. According to the thermal transfer method, a coloring matter is sublimated so as to be transferred onto the image receiving sheet.
Moreover, as another image forming method onto an image receiving sheet, an ink-jet method for forming an image by ejecting ink droplets without thermal transfer can be presented. An apparatus for the ink-jet method comprises a plurality of nozzle holes with ink heads provided parallel, independent ejecting rooms communicating with the nozzle holes with a part of the wall serving as an oscillating plate, a piezoelectric element mounted on the oscillating plate, and a common ink cavity for supplying an ink to the ejection rooms so that a pulse voltage based on the image information is applied onto the piezoelectric element for mechanically deflecting the oscillating plate for increasing or reducing the capacity of the ejecting rooms, and ejecting ink droplets from the nozzle holes, utilizing the pressure in the rooms changed momentarily so as to form an image on an image receiving sheet.
The method of using a thermal head in the thermal transfer method involves a problem in that the temperature distribution can easily be uneven due to irregularity of the heat resistance value, resulting in generation of irregularity in the formed image.
Moreover, a problem of the supporting member deformation due to local high temperature heating, resulting in liability of wrinkle generation also arises.
Furthermore, the method of using a laser beam in the thermal transfer method involves a problem of too high an apparatus cost. Moreover, a problem of liability of image irregularity due to the material decomposition by high temperature momentary heating also arises.
In contrast, according to the ink-jet method, for avoiding nozzle choking and for stably forming drops, an image forming material cannot be selected freely due to various limitations on the image forming material in terms of the liquid physical properties. For example, even in the case of forming a color image, in order to prevent nozzle choking, a dye or a specific pigment should be selected so that the same hue as the printing ink pigment cannot be reproduced. Therefore, it cannot be adopted in a highly sophisticated printing proof printer, and thus it is problematic. Moreover, problems of low light resistance and water resistance of a formed image, and liability of blurring of the dye on the image receiving member are involved.
As a method for solving the problems, a new method, a related art of the invention, has been filed as Japanese Patent Application No. 11-170702.
The invention of the patent application comprises the steps of preparing a transfer member having an image forming material, forming a latent image by ejecting liquid droplets containing a material for improving the transfer sensitivity onto either one of the transfer member or an image receiving member to form an image, closely contacting the transfer member and the image receiving member with the latent image interposed therebetween, passing a pressure roller heated at a temperature lower than the temperature capable of transferring the part without the latent image formation by the material for improving the transfer sensitivity and sufficient for transferring the latent image formation part by the material for improving the transfer sensitivity, and peeling off the transfer member and the image receiving member so as to form the transfer image on the image receiving member as the above-mentioned image.
In the image forming method, the transfer member is separated from the supporting member only in the part with the latent image formation so as to be transferred for forming the image on the image receiving member surface.
According to the method, an image can be obtained with a good quality. However, in contrast, in the case of forming an image with a plurality of colors in the method, formation of a second or subsequent color image may be influenced by the latent image of a preceding image so that the image range of the part can be wider than the targeted area.
As mentioned above, in forming an image with a plurality of colors using the new method, since formation of a second or subsequent color image may be influenced by the latent image of a preceding image, a problem arises in that the image range of the part can be wider than the targeted area.
In order to solve the above-mentioned problems, a first aspect of the invention is an image forming method for forming an image on an image receiving sheet, using a transfer sheet provided with at least two layers including an intermediate layer having a function of preventing permeation of a moisture content, a surfactant or the like and a thermally fusible ink layer in this order on a supporting member, and the image receiving sheet for transferring the thermally fusible ink layer thereon, wherein a solution for improving the transfer sensitivity is applied according to the image on either of the transfer sheet or the image receiving sheet.
Moreover, a second aspect of the invention is a transfer sheet to be used in an image forming method for forming an image on an image receiving sheet, using a transfer sheet provided with at least two layers including an intermediate layer having a function of preventing permeation of a moisture content, a surfactant or the like and a thermally fusible ink layer in this order on a supporting member, and the image receiving sheet for transferring the thermally fusible ink layer thereon, wherein a peeling layer is provided between the supporting member and the intermediate layer.
Furthermore, a third aspect of the invention is a transfer sheet to be used in an image forming method for forming an image on an image receiving sheet, using a transfer sheet provided with at least two layers including an intermediate layer having a function of preventing permeation of a moisture content, a surfactant or the like and a thermally fusible ink layer in this order on a supporting member, and the image receiving sheet for transferring the thermally fusible ink layer thereon, wherein a surface layer is provided on the surface of the thermally fusible ink layer.
Still further, a fourth aspect of the invention is a transfer sheet to be used in an image forming method for forming an image on an image receiving sheet, using a transfer sheet provided with at least two layers including an intermediate layer having a function of preventing permeation of a moisture content, a surfactant or the like and a thermally fusible ink layer in this order on a supporting member, and the image receiving sheet for transferring the thermally fusible ink layer thereon, wherein a back layer is provided on the back side of the supporting member.
Moreover, a fifth aspect of the invention is the transfer sheet according to any of the second to fourth aspects, wherein a polyamide resin is included as an additive material to be added in the intermediate layer.